1. Field of the Invention
The present invention relates to novel cortistatin polypeptides, and to polynucleotides encoding these polypeptides. More specifically, isolated nucleic acid molecules are provided encoding a Human Cortistatin polypeptide. Cortistatin polypeptides are also provided, as are vectors, host cells and recombinant methods for producing the same. Also provided are diagnostic methods for detecting variations in Human Cortistatin gene expression and therapeutic methods for treating individuals in need of an increased level of Human Cortistatin activity.
2. Related Art
The 1970""s saw the initiation of a great amount of scientific discovery and research into the regulation of hormone release, especially by neuropeptides. Somatostatin, a 14 mer cyclic polypeptide was one of these neuropeptide hormone regulators. It was discovered to be released primarily in the hypothalamus, and to inhibit Growth Hormone (GH) secretion from the pituitary gland, and to decrease the GH response to secretagogues. Somatostatin is also found throughout the brain and serves as a neurotransmitter in many areas, including the spinal cord, brain stem, and cerebral cortex. It is also present in the gastrointestinal tract, where the D cells of the pancreatic islets regulate insulin and glucagon secretion.
There has been a lot of interest in studying the actions of somatostatin and analogues for efficacy in the therapy of acromegaly, secretory pancreatic tumors, pancreatitis, acute gastric ulcers and stress gastritis.
Thus, there is a continuing need in the art for isolating novel hormone-regulating peptides, especially neuropeptides of human origin, useful for therapy in various hormone mediated processes.
The present invention provides isolated nucleic acid molecules comprising a polynucleotide encoding the Human Cortistatin polypeptide having the amino acid sequence shown in FIG. 1 (amino acid residues xe2x88x9219 to 86 in SEQ ID NO:2) or the amino acid sequence encoded by the cDNA clone deposited in a bacterial host as ATCC Deposit Number 97639 on Jun. 27, 1996. The nucleotide sequence determined by sequencing the deposited Cortistatin clone, which is shown in SEQ ID NO:1, contains an open reading frame encoding a polypeptide of 105 amino acid residues, including an initiation codon at positions 46-48 in SEQ ID NO:1, with a leader sequence of about 19 amino acid residues, and a predicted molecular weight of about 12 kDa. The amino acid sequence of the mature Cortistatin protein is shown in FIG. 1 (amino acid residues from about 1 to about 86 in SEQ ID NO:2).
Thus, one aspect of the invention provides an isolated nucleic acid molecule comprising a polynucleotide having a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the Human Cortistatin polypeptide having the complete amino acid sequence in SEQ ID NO:2; (b) a nucleotide sequence encoding the Human Cortistatin polypeptide having the amino acid sequence at positions from about xe2x88x9218 to about 86 in SEQ ID NO:2; (c) a nucleotide sequence encoding the mature Human Cortistatin polypeptide having the amino acid sequence at positions from about 1 to about 86 in SEQ ID NO:2; (d) a nucleotide sequence encoding the polypeptide having the amino acid sequence at positions from about 58 to about 86 in SEQ ID NO:2; (e) a nucleotide sequence encoding the Human Cortistatin polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97639; (f) a nucleotide sequence encoding the mature Human Cortistatin polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97639; and (g) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b), (c), (d), (e), or (f) above. Preferably, the nucleic acid molecule will encode the mature polypeptide in SEQ ID NO:2 or encoded by the above-described deposited cDNA.
Further embodiments of the invention include isolated nucleic acid molecules that comprise a polynucleotide having a nucleotide sequence at least 95% identical, and more preferably at least 96%, 97%, 98% or 99% identical, to any of the nucleotide sequences in (a), (b), (c), (d), (e), (f), or (g), above, or a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide in (a), (b), (c), (d), (e), (f), or (g), above. This polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues.
An additional nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a Human Cortistatin polypeptide having an amino acid sequence in (a), (b), (c), (d), (e), (f), or (g), above.
The present invention also relates to recombinant vectors, which include the isolated nucleic acid molecules of the present invention, and to host cells containing the recombinant vectors, as well as to methods of making such vectors and host cells and for using them for production of Cortistatin polypeptides or peptides by recombinant techniques.
The invention further provides an isolated Human Cortistatin polypeptide having an amino acid sequence selected from the group consisting of: (a) the amino acid sequence of the Human Cortistatin polypeptide having the complete 105 amino acid sequence, including the leader sequence shown in SEQ ID NO:2; (b) the amino acid sequence of the Human Cortistatin polypeptide lacking the N-terminal methionine residue having the amino acid sequence at positions from about xe2x88x9218 to about 86 in SEQ ID NO:2; (c) the amino acid sequence of the mature Human Cortistatin polypeptide (without the leader) having the amino acid sequence at positions from about 1 to about 86 SEQ ID NO:2; (d) the amino acid sequence of the polypeptide having the amino acid sequence at positions from about 58 to about 86 SEQ ID NO:2; (e) the amino acid sequence of the Human Cortistatin polypeptide having the complete amino acid sequence, including the leader, encoded by the cDNA clone contained in ATCC Deposit No. 97639; and (f) the amino acid sequence of the mature Cortistatin polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No.97639.
An additional embodiment of this aspect of the invention relates to a peptide or polypeptide which has the amino acid sequence of an epitope-bearing portion of a Cortistatin polypeptide having an amino acid sequence described in (a), (b), (c), (d), (e), or (f), above. Peptides or polypeptides having the amino acid sequence of an epitope-bearing portion of a Cortistatin polypeptide of the invention include portions of such polypeptides with at least six or seven, preferably at least nine, and more preferably at least about 30 amino acids to about 50 amino acids, although epitope-bearing polypeptides of any length up to and including the entire amino acid sequence of a polypeptide of the invention described above also are included in the invention. In another embodiment, the invention provides an isolated antibody that binds specifically to a Cortistatin polypeptide having an amino acid sequence described in (a), (b), (c), (d), (e), or (f) above.
The invention further provides methods for isolating antibodies that bind specifically to a Cortistatin polypeptide having an amino acid sequence as described herein.
The present inventors have discovered that Cortistatin is expressed primarily in the brain, especially in the putamen. For a number of disorders, significantly higher or lower levels of Cortistatin gene expression can be detected in brain, especially putamen, tissue or bodily fluids (e.g., serum, plasma, urine, synovial fluid or spinal fluid) taken from an individual having such a disorder, relative to a xe2x80x9cstandardxe2x80x9d Cortistatin gene expression level, i.e., the Cortistatin expression level in brain tissue or bodily fluids from an individual not having the disorder. Thus, the invention provides a diagnostic method useful during diagnosis of a neurological disorder, which involves (a) assaying Cortistatin gene expression level in cells or body fluid of that individual; (b) comparing that Cortistatin gene expression level with a standard Cortistatin gene expression level, whereby an increase or decrease in the assayed Cortistatin gene expression level compared to the standard expression level is indicative of said neurological disorder.
An additional aspect of the invention is related to a method for treatment of an individual in need of an increased level of Cortistatin activity in the body comprising administering to such an individual a composition comprising an isolated Cortistatin polypeptide of the invention.